Nanowire optical/electrical properties

Figure 11.2. Nanowire electronic and optical properties, (a) Schematic of an NW-FET used to characterize electrical transport properties of individual NWs. (inset) SEM image of an NW-FET two metal electrodes, which correspond to source and drain, are visible at the left and right sides of the image, (b) Current versus voltage for an n-type InP NW-FET. The numbers inside the plot indicate the corresponding gate voltages (Vg). The inset shows current versus Vg for Fsd of 0.1 V. (c) Real-color photoluminescence image of various NWs shows different color emissions, (d) Spectra of individual NW photoluminescence. All NW materials show a clean band-edge emission spectrum with narrow FWHM around 20nm. (See color insert.)...

A whole new chemistry has been developed around this discovery, and the unusual properties have given rise to suggestions that it could be made into products for a superconducting material, a three-dimensional polymer, new catalysts, new materials with unusual electrical and optical properties and very high mechanical strength, sensors, nanotubes, nanowires, and so on. At this moment, there are, as yet, no products based on the fullerene on the market. 

TTie subject of nanotechnology thus now covers the search for and synthesis of new materials of advanced technology which possess the sizes of nanometres the determination of their characteristics, and their practical application. Nanostructures are the bridge between individual atoms and molecules, where the laws of quantum mechanics apply, and bulk phases, whose properties usually result from the collective behaviour of billions of atoms. Individual nanostructures may be clusters, nanomolecules, nanocrystals, so-called quantum points, nanowires and nanotubes. They possess orderly structures and some large molecules can form single nanostructures [2], The quantum sizes and shapes of nanomolecules affect their mechanical, chemical, electrical, nuclear-electronic, electric-optical and dynamic properties. They may exhibit new, unique physicoehemical phenomena, quantitatively different from those of the bulk phase. This leads to the possible control of the action and application of nanostructures... 

By changing the doping level, dopant, and template-dissolving solvents, the electrical and optical properties of the nanotubes and nanowires can be controlled. The diameters of the conducting polymer nanotubes and nanowires are in the range 100-200 nm, depending on the diameter of the nanoporous template used, it was found that the polymerization was initiated from the wall-side of the AAO template. The synthesized nanotubes have an open end at the top with the filled end at the bottom. As polymerization time increases, the nanotubes will be filled and nanowires will be formed with the length increased. For example,... 

Semiconducting one-dimensional (ID) nanolibers or nanowires are of interest for a wide variety of applications including interconnects, functional devices, and molecular sensors as well as for fundamental physics studies. Devices have been fabricated fi om semiconductor, and carbon nanotubes, and more recently from ICP nanofibers. It has been predicted that ICP nanofibers will have unique electrical, optical, and magnetic properties [134]. Several different methods for producing these ICP nanofibers have been developed with or without the aid of a template. The template-based methods involve synthesizing a tubular structure of the ICP within the pores of a support membrane, such as an alumina membrane [135] or a track-etched polycarbonate membrane [136]. However, more recent work has... 

Seong HK, Choi HJ, Lee SK, Lee J, Choi DJ (2004) Optical and electrical transport properties in silicon carbide nanowires. Appl Phys Lett 85 1256... 

Qiu T, Wu XL, Siu GG, Chu PK (2005) Self-assembled growth and green emission of gold nano whiskers. Appl Phys Lett 87 223115-1-223115-3 Qu Y, Liao L, Li Y, Zhang H, Huang Y, Duan X (2009) Electrically conductive and optically active porous silicon nanowires. Nano Lett 9(12) 4539 543 Qu Y, Zhong X, Li Y, Liao L, Huang Y, Duan X (2010) Photocatalytic properties of porous silicon nanowires. J Mater Chem 20(18) 3590-3594... 

Nanowires (NWs), like CNTs, are also one-dimensional and well-defined crystalline structure with a high aspect ratio. NWs have demonstrated superior electrical, optical, mechanical and thermal properties. Unlike CNTs, NWs are noncarbon based materials that can consist of metals, semiconductors, or inorganic... 

Single crystal nanowires (SNW) are one-dimensional single crystal nanopartides like fullerenes vs. carbon nanotubes. While retaining the properties of nanopartides, SNW have been made into functional devices such as transistors, nanoelectrode arrays, and probes for biological sensing. Depending on the materials type and diameter, SWN and devices can be made electrically, optically, or magnetically functional. 

Au nanorods (NRs) are particularly useful for biological applications since their near-field and far-field optical properties can be tuned controllably throughout the NIR water window by varying their geometry [34], Metallic nanorods and nanowires can have enhanced electric fields at the tips compared to spheres, which would lead to increased SERS activity [1, 35-38]. Moreover it has been shown that Ag cylinders or nanorods exhibit extraordinary electrocataljAic activities towards the electro-reduction process, especially in the case of benzyl chloride [29]. 

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